Conventional phase array is applied in communication system or search radar, and includes an antenna array which can increase the signal intensity in a specific direction and decrease the signal intensity in other directions for beamforming by controlling the phase of the signals radiated from each antenna. The beam covering the target communication device or subject can decrease the beam influence on other devices or the influence of environment noise on the phase array for improving the communication or search capability.
With reference to FIG. 1, a passive phase array 200 includes a plurality of antenna elements 210 and a transceiver module 220, wherein the antenna elements 210 are coupled to the transceiver module 220 by a power splitter. Each of the antenna elements 210 includes an antenna 211, an amplifier 212 and a phase shifter 213, wherein each signal is transmitted to each antenna element 210 via the power splitter, then phase-shifted by the phase shifter 213 and amplified by the amplifier 212, and finally radiated from the antenna 211. The phase shifter 213 of each of the antenna elements 210 shifts the phase of each of the signals to stack and cancel the signals with each other for forming a beam. The passive phase array 200 can form the beam with different direction, but this architecture needs more active control elements to control the signals, which increase the power loss, the control complexity and the cost.